Synchronous Dynamic Random Access Memory (SDRAM) is a type of Random Access Memory (RAM) used in computing devices. SDRAM comprises both single data rate (SDR) SDRAM and double data rate (DDR) SDRAM. SDR SDRAM transfers data during each period of a timing signal in synchronization with a rising edge of the timing signal. By contrast, DDR SDRAM can achieve nearly twice the bandwidth of SDR SDRAM by transferring data on both rising and falling edges of a timing signal.
To transfer data from an SDRAM memory module to a memory controller, the memory controller may initiate a read operation by issuing a read request to the memory module. After a period of time has elapsed, the memory module may respond by transmitting a data signal along with a timing signal (e.g., DQ data signal and DQS data strobe signal) to the memory controller. In some systems, the timing signal undergoes a filtering operation prior to receipt at the memory controller to eliminate signal noise and/or undesirable regions of the timing signal. In response to receiving the timing signal, the memory controller may read the data signal and store data by registering data on rising and/or falling edges of the timing signal.
Due to clock jitter and/or changes in temperature or voltage that may occur in the system, the response from the memory module may require a variable amount of time. If a filtering operation is to be performed on the timing signal prior to its receipt at the memory controller, the variable nature of the memory module's response may be problematic. For example, a filtering element that is configured to operate at a static, pre-determined time interval following the read request may be unable to compensate for the variable nature of the timing signal, causing an incorrect filtering operation. The incorrect filtering operation may result in erroneous data read operations, which may lead to a variety of problems, including a reduction of system performance and/or data corruption in the memory controller.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.